To put s.t. inside of s.t. else; to insert s.t. into s.t. [pa--un]; to go into or inside s.t. [pa-].
I'm keeping (lit. putting) what you said in my mind.
Put a half gallon of gasoline in that motorcycle.
Insert your machete (in its sheath).
When I was about to spear that crab, it immediately went into its hole.